Sealing disc for metallic cap closures, crown closures or the like



GER 2,901,139 P CLOSURES, CROWN Aug. 25, 1959' A. ISELEAREG SEALING DISCFOR METALLIC CA INVENTOR. W720 @626 -U/Zgg 99i 'DJMwM United StatesPatent 6 SEALING DISC FOR METALLIC CAP CLOSURES,

CROWN CLOSURES OR THE LIKE Alfons Isele-Aregger, Immensee, CantonSchwyz, Switzerland, assignor, by mesne assignments, to Union CarbideCorporation, a corporation of New York Application January 16, 1956,Serial No. 559,445 Claims priority, application Germany January 26, 19555 Claims. (Cl. 21540) The present invention relates to closures,particularly to closures for food and beverage containers, such as crownclosures, metallic cap closures, screw-on closures and the like, andespecially, to sealing means therefor.

The present application is a continuation-in-pant of my prior copendingapplication Serial No. 365,842, filed July 3, 1953, on Bottle Closures.

The problem of replacing the well-known cork sealing disc in metalliccap closures, crown closures, or the like by other materials has, sincethe development of the plastic industry, been the subject of a greatmany con siderations. Many proposals 'have found expression in patentliterature of remarkable importance, but nevertheless, a reallypractical sealing disc meeting with full success has not heretofore beenafforded.

In the case of food products, the material of the seal must meet theabsolute requirement that the seal may in no way affect the smell andtaste of the contents of the bottle or jar. Materials which fullysatisfy this condition are, for example, certain plasticizer-freeartificial substances, especially polyethylene. Polyethylene, however,has the disadvantage that it is to a certain extent permeable to gas,which normally would render the material unsuitable for sealing vacuumand pressure packed foods and beverages, particularly the latter.

According to the present invention, a polyethylene seal, suitably asealing disc, is effectively rendered impermeable to gas by theprovision of contact surfaces on the disc engageable with the top faceof the bottle and with the inner surface of the metallic cap which arekept as small as possible, the mutual contact of these parts prior topressing of the cap onto the container being substantially linear. Byvirtue of this relationship, after the cap has beenpressed onto thecontainer, a high specific pressure will be obtained in the narrowcontact zone. The sealing material, accordingly, is compressed to a verysubstantial extent in the contact zone, thus to prevent passage of gastherethrough.

In practice, the linear seal above defined may be obtained by providinga sealing disc having a thin central portion with an annular padsurrounding the same, the pad preferably being circular, elliptical, orsquare in cross-section, or if desired, comprising a plurality ofconcentric annular pads. It has been found that a pad of ellipticalcross-section is particularly capable of withstanding extremely highpressure wi-thin a container.

Inasmuch as the seal according to the invention takes place in a smallarea or region at high specific pressure, the sealing disc need includeonly a small portion of predetermined thickness in the region of thesealing zone, dependent on the species and properties of the selectedmaterial. For this reason it is possible in the remaining regions of theseal to maintain the sealing disc relatively thin, since the centralportion of the disc serves only to prevent contact of the contents ofthe container with the metallic cap, and since the marginal portion ofthe disc need serve nomore than to assist the cap onto the bottle, thecontact line of the disc 2,901,139 Patented Aug. 25 195 9 in retainingthe seal in the cap and, in certain cases, to prevent the metal cap fromhearing directly on the mouth or lip of the container. Accordingly, thesealing inserts or discs may be manufactured in an extremely economicalmanner.

Special attention is directed to the arrangement of the annular pad.Heretofore, those skilled in the art have been of the opinion that theseal on bottles with crown closures must take place in the outer regionof the mouth or lip of the bottle, and preferably at the point where themouth or lip is inclined, as defined by the inclination of the tangentof that surface toward the horizontal, at an angle of about 45 or more,the seal being effected over a large area commencing at the pointindicated and extending inwardly approximately to a diametercorresponding to the inner diameter of the mouth of the bottle plustwice half the thickness of the wall defining the mouth or lip of thebottle.

Extensive tests have shown that this generally prevailing opinion iserroneous and that an appreciably better seal in cap closures of allkinds will be obtained if the sealing area is maintained small and thediameter of the line of sealing engagement, as provided according to theinvention, is at most equal approximately to the inner diameter of themouth of the bottle plus twice of the thickness of the wall of the mouthor sealing lip. Sealing discs designed in accordance with the presentinvention withstand pressures which are approximately twice as high asthose obtained with sealing discs of conventional forms.

A further feature of the invention is the provision of sealing discsformed in such manner as to be quite symmetrical with respect to thehorizontal median plane of the seal. Thus, insertion of the sealingdiscs into metallic caps is appreciably simplified, inasmuch as bothsurfaces of the disc are identical, and it is therefore immaterial howthe discs are inserted in a cap. The defined symmetry permits ofsimplified handling of the seals on crown cap assembly machines and thelike particularly as compared to the unsymmetrical discs proposedheretofore.

In the industry concerned, it has heretofore been a problem to assemblea sealing disc with a metallic cap is entirely excluded, because ahollow space exists between the metallic cap and the sealing disc in thecentral area of the seal due to the symmetry of the relatively thicksealing pad. The disc of the invention must therefore be anchored in theclosure in another manner, and to this end, I employ the edge of theseal as a lateral contact surface for engagement in the metallic cap. Inorder to attain the desired adhesion, the outer diameter of the sealingdisc must, on one hand, be somewhat greater than the inner diameter ofthe metallic cap and must, on the other hand, be given a special shapefor efiecting a tension and friction grip in the cap. The stated objectis suitably achieved by thickening or cormgating the outer marginal zoneof the sealing disc, or providing it with serrations.

The present invention lies consequently in the combination of thefeatures that the sealing disc is quite symmetrical with respect to themedian plane, has a thin central portion with an annular pad surroundingthe same, and has a marginal rim surrounding the pad, the pad havinglinear contact with respect to the mouth of the bottle and the metalliccap prior to the pressing of He t?! mea t e nne diam er cine-me p d. sge q .q f% cd net d: cr thi ken d, .BYP L E i Q. t ese. eq ined v e retg e e am litnum eifect is obtained. Among other things, itwill be pqe hltqlbave he. me ll cqan' d s n q w hin e wherebysubstantial sayings ofmaterial aremade, he ob c s..a d,,. dy t s 9 he in en o will gi nimr n0. ski l i t e an and l becom 'in entin he fo win e c i nn a. pr err d lq me lt l e nventi n whe e i e cn e smad t fl eaq pslb i y a rew n rshcwsabv y ainple, preferred embodiments of the invention.

n. th d a s; .i H figure 1 is a cross-sectibnal view of the neck prmouth of a bottle, a crown closure, and pneembodiment of the improvedseal of the i nve ntion, the closure and seal being shown as set on thebottle, but not secured hsa tqw H. r, n 1 Figure 2 is a plan view of thesealing disc'of Figure l; and r Fighre} is a cross sectional view of asecond embodiment of my improved sealing disc.

As shown the sealing disc comprises a thin circular central portion 1,an annular pad 2 surrounding the central portion, and a rim 4surrounding the pad 2, the being separated from thepad Z by'a thinannular flexible portion 1a of the disc, The pad 2 is shown in Figuresland 2 as being elliptical in cross sectio'n, but the same'may suitablybe of circular or square cross-section, ormay suitably comprise aplurality of concentric ridges, beads or; pads, as shown at 2:1 inEigui-e When positioned as shown in Figure .1, wherein the seal isrested on the mouth ofthe bottle, and the cap is rested'on the seal, thepad 2 contacts the mouth of the bottle'alon'g the circular line 5 andcontacts the cap along the circular line 6,.the contact line Slyingnearer to the opening 7 in the bottle than to the HP 8 of the bottle. Toinsure a firm frictional, adhesive fit of the disc within the metalliccap 3, the rim 4 of the disc the inner diameter of the'clo'sure, and theriin is beaded.

.When the closure 3 is secured to the lip 8 of'the bottle, the sealingdisc of Figures 1 and 2 is com-' pressed to' a substantial extent in thearea of the pad 2 thereof to define small area annular sealing surfaceson the opposite sides of the pad engaging respectively against the mouthof the bottle and the inner surface of the closure. Due to the smallarea of contact, sealing pressure per unit-"area is high and the pad 2is com:

pressedto render the same impermeable to gas even.

though the seal is formed ofpla'sticizer free polyethylene. In likemanner,- the sealing disc of Figure 3 is compressed in the area of thepad thereof with each of the ridges or beads Za'defining a very smallarea annular sealing surface for the purposes stated.v The ridges are inherently more flexible than a solid pad and thus are optimumly suitedfor sealing against irregular surfaces sueh as the mouth of a glassbottle.

In'both embodiments, the head or rim 4 is of a diam eter greaterthanflthe inner diameter of therim portion of the closure to be fittedfrictionally therein, thethin annular portion between the .rim' and padflexing, and the rim itself having a relatively large peripheral'su rface area, to insure a retentive fit of the disc in the closure.Moreover, the rim 4, upon attachment of the closure to thebottle, isforced into small sui'face area sealingengagement with the outerportions of the mouth of t-he, bottle to afford a s'econdary'seal'a'ndasecondary area of high compression acting as a safeguar'd'to the" sealetfectedat the pad Zor 2a.

has an outer diameter greater than.

48 $1 1 5 .f l'm da' hesealinsd c...0f. the. invention is far superiorto the conventional cork disc seal, since the seal of the invention iscapable of withstanding higher internal pressures. Moreover, the presentinvention afiords a sealing disc formed of plastic materials whichsatisfies all the requirements to tastelessness, gas impermeability,tightness, saving in material, and fiirhat- 1 tachment of the-discwithin the cap or closure.

engagement with the mouth of the While I have shown what I regard to bethe preferred embodiments otniy inv'ention, and have described these andother suitable embodiments of the invention; itis apparent that variouschanges, rearrangements and modifications'rnay be made"therein withoutdeparting from the scope of the invention, as defined by the appendedclaims.

I claim:

1. A sealing disc for bottle closures and the like, comprising agenerally planar polyethylene disc, said disc Being symmetrical inrelation to the median thereof and including a thin circular centralportion, an annular pad encircling said central portion,;saidpad beingof elliptical shape in cross-section and 'de'fining a line contact onfipposite sides thereoffor engagement, respectively, with the mouth of abottle and the inner surface of a closure prior to attachment of theclosure to the bottle, the line contact on said pad for' e gage: mentwith the mouth of the bottle being at most of a diameter equalapproximately to the diameter of the bottleopening plus twice of thethickness of the wallof the bottle El'efiiiingth'e opening, a thinannula portion encircling said pad, and annular marginal rim encirclingsaid last naniedfportion, said riin'being of an outer diameter" greaterthan the inner nam of the crest-ire and being headed t define 'n saiddisc a ma'rginal edge of substantial area, said rir'n being adapted tobe fitted frietionally within theclosure and to engage the closure overa substantial area detachably to secure the seal within the closure. I i

2. Af'sealing disc for bottle closures and the like, comprising agenerally planar polyethylene disc, said disc being symmetrical inrelation to the median plane thereof and including a thin circularcentralportion, an

tral portion, the outer sealings urface on said pad for bottle being atnit 5st of"?! diameter equal approximately to the diameter of the bottleopening plus twice 75% of the thickness of the wall of the bottledefining the opening; a thin an nular'portion encircling said pad, andan annular'niarginal encircling sa'id last-named portion, said rim beingof an outer diameter greater than the inner diam; eter of the closureand being'beaded to define on said disc a marginal edge of substantialarea and to define the outer margin thicker than the thin annularportion, said thin annular portion further spacing said beaded marginalrin:i from the outermost of said coii cen tric beads, said rim beingadapted to be fitted frictionally within the closure and to engage theclosure overa' substantial area by the action of said thin annularportion and said beaded marginal edge de'tachably to secufe'thes ealwithin the closure. 7

3.;A seal for crown type bottle closures and the like, firing agenerally planar imperforate polyethylene said isc being symmetrical inrelation to both its med an'plan andits axis and including athin c'irc'central 'pbrtion'; annular sealing rne ans enci'r c g said centralportion and defining circular sealing""surfaces" on the opposite sidesthereof for engagement, respectively, with the mouth of a bottle and theinner surface of a crown closure, said sealing surfaces on each sidebeing spaced apart in the form of concentric ridges, a thin flexibleannular portion encircling said annular sealing means, and an annularmarginal bead encircling said thin flexible annular portion, said thinannular portion having a radial width at least equal to the radial widthof said annular marginal bead, said bead being of an outer diametergreater than the inner diameter or the closure and being of a thicknessgreater than the thickness of the thin annular portion, and having anouter edge of substantial area to fit frictionally within and engage theside wall of the closure, said thin flexible annular portion and saidedge of said bead cooperating to assist in accomplishing a retentive fitof said disc in the closure.

4. A seal for a closure comprising a disc including a thin circularcentral portion, an annular sealing pad encircling said central portion,a thin flexible annular portion encircling said pad, and an annularmarginal bead encircling said thin flexible annular portion, saidannnular sealing pad being of greater thickness transversely of saiddisc than said annular marginal bead, said head being of an outerdiameter greater than the inner diameter of the closure and having anouter edge of substantial area to fit frictionally within and engage theside wall of the closure, said thin flexible annular portion and saidedge of said bead insuring a retentive fit of said disc in the closure.

5. A seal for crown type bottle closures and the like, comprising ageneral-1y planar imperforate plastic disc, said disc being symmetricalin relation to both its median plane and its axis and including a thincircular central portion, an annular sealing pad encircling said centralportion anddefining circular sealing surfaces on the opposite sidesthereof for engagement, respectively, with the mouth of a bottle and theinner surface of a crown closure, a thin flexible annular portionencircling said pad, and an annular marginal bead encircling said thinflexible annular portion, said annular sealing pad being of greaterthickness transversely of said disc than said annular marginal bead,said bead being of an outer diameter greater than the inner diameter ofthe closure and having an outer edge of substantial area to fitfrictionally within and engage the side wall of the closure, said thinflexible annular portion and said edge of said bead insuring a retentivefit of said disc in the closure.

References Cited in the file of this patent UNITED STATES PATENTS785,116 Perry Mar. 21, 1905 2,073,415 Enkur Mar. 9, 1937 2,765,943 WolfiOct. 9, 1956 FOREIGN PATENTS 162,427 Australia Apr. 13, 1955 523,527Belgium Oct. 31, 1953 1,020,206 France Nov. 12, 1952

